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perf: improves looping performance
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- only check for 'statementLike' once per node-array
- cache property access
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@acutmore
acutmore committed Sep 10, 2024
1 parent 7e770e7 commit 8a8eddf
Showing 1 changed file with 77 additions and 59 deletions.
136 changes: 77 additions & 59 deletions src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -59,7 +59,7 @@ export function blankSourceFile(source: ts.SourceFile, onErrorArg?: ErrorCb): st
scanner.setText(input);
ast = source;

ast.forEachChild(visitStatementLike);
visitNodeArray(ast.statements, /* isStatementLike: */ true, /* isFunctionBody: */ false);

return str.toString();
} finally {
Expand All @@ -74,25 +74,36 @@ export function blankSourceFile(source: ts.SourceFile, onErrorArg?: ErrorCb): st
}
}

function visitHelper(visitor: typeof innerVisitor, node: ts.Node, knownStatementLike: boolean): VisitResult {
function visitUnknownNodeArray(nodes: ts.NodeArray<ts.Node>): VisitResult {
if (nodes.length === 0) return VISITED_JS;
return visitNodeArray(nodes, tslib.isStatement(nodes[0]), /* isFunctionBody: */ false);
}

function visitNodeArray(nodes: ts.NodeArray<ts.Node>, isStatementLike: boolean, isFunctionBody: boolean): VisitResult {
const previousParentStatement = parentStatement;
if (knownStatementLike || tslib.isStatement(node)) {
parentStatement = node;
}
const r = visitor(node, node.kind);
if (r === VISITED_JS) {
seenJS = true;
const previousSeenJS = seenJS;
if (isFunctionBody) {
seenJS = false; // 'seenJS' resets for nested execution context
}
for (let i = 0; i < nodes.length; i++) {
const n = nodes[i];
if (isStatementLike) {
parentStatement = n;
}
if (visitStatementLike(n) === VISITED_JS) {
seenJS = true;
}
}
parentStatement = previousParentStatement;
return r;
}

function visitStatementLike(node: ts.Node): void {
visitHelper(innerVisitStatementLike, node, /* knownStatementLike */ true);
if (isFunctionBody) {
seenJS = previousSeenJS;
}
return seenJS ? VISITED_JS : VISIT_BLANKED;
}

function innerVisitStatementLike(node: ts.Node, kind: ts.SyntaxKind): VisitResult {
function visitStatementLike(node: ts.Node): VisitResult {
const n = node as any;
const kind = node.kind;
switch (kind) {
case SK.ImportDeclaration:
return visitImportDeclaration(n);
Expand All @@ -108,15 +119,16 @@ function innerVisitStatementLike(node: ts.Node, kind: ts.SyntaxKind): VisitResul
}

function visitor(node: ts.Node): VisitResult {
return visitHelper(innerVisitor, node, /* knownStatementLike: */ false);
const r = innerVisitor(node, node.kind);
if (r === VISITED_JS) seenJS = true;
return r;
}

function innerVisitor(node: ts.Node, kind: ts.SyntaxKind): VisitResult {
const n = node as any;
// prettier-ignore
switch (kind) {
case SK.Identifier: return VISITED_JS;
case SK.Block: return node.forEachChild(visitStatementLike) || VISITED_JS;
case SK.VariableDeclaration: return visitVariableDeclaration(n);
case SK.VariableStatement: return visitVariableStatement(n);
case SK.CallExpression:
Expand Down Expand Up @@ -144,7 +156,7 @@ function innerVisitor(node: ts.Node, kind: ts.SyntaxKind): VisitResult {
case SK.TypeAssertionExpression: return visitLegacyTypeAssertion(n);
}

return node.forEachChild(visitor) || VISITED_JS;
return node.forEachChild(visitor, visitUnknownNodeArray) || VISITED_JS;
}

/**
Expand All @@ -155,7 +167,7 @@ function visitVariableStatement(node: ts.VariableStatement): VisitResult {
blankStatement(node);
return VISIT_BLANKED;
}
node.forEachChild(visitor);
node.forEachChild(visitor, visitUnknownNodeArray);
return VISITED_JS;
}

Expand All @@ -168,8 +180,9 @@ function visitCallOrNewExpression(node: ts.NewExpression | ts.CallExpression): V
blankGenerics(node, node.typeArguments);
}
if (node.arguments) {
for (let i = 0; i < node.arguments.length; i++) {
visitor(node.arguments[i]);
const args = node.arguments;
for (let i = 0; i < args.length; i++) {
visitor(args[i]);
}
}
return VISITED_JS;
Expand Down Expand Up @@ -237,7 +250,7 @@ function visitClassLike(node: ts.ClassLikeDeclaration): VisitResult {
}
}
}
node.members.forEach(visitStatementLike);
visitNodeArray(node.members, /* isStatementLike: */ true, /* isFunctionBody: */ false);
return VISITED_JS;
}

Expand All @@ -252,30 +265,37 @@ function visitExpressionWithTypeArguments(node: ts.ExpressionWithTypeArguments):
return VISITED_JS;
}

const classElementModifiersToRemoveArray = [
SK.AbstractKeyword,
SK.DeclareKeyword,
SK.OverrideKeyword,
SK.PrivateKeyword,
SK.ProtectedKeyword,
SK.PublicKeyword,
SK.ReadonlyKeyword,
] as const;
const classElementModifiersToRemove = new Set(classElementModifiersToRemoveArray);

function isRemovedModifier(kind: ts.SyntaxKind): kind is (typeof classElementModifiersToRemoveArray)[number] {
return classElementModifiersToRemove.has(kind as never);
}

function visitModifiers(modifiers: ArrayLike<ts.ModifierLike>): void {
for (let i = 0; i < modifiers.length; i++) {
const modifier = modifiers[i];
switch (modifier.kind) {
case SK.PrivateKeyword:
case SK.ProtectedKeyword:
case SK.PublicKeyword:
case SK.AbstractKeyword:
case SK.OverrideKeyword:
case SK.DeclareKeyword:
case SK.ReadonlyKeyword:
blankExact(modifier);
continue;
case SK.Decorator:
visitor(modifier);
continue;
const kind = modifier.kind;
if (isRemovedModifier(kind)) {
blankExact(modifier);
continue;
} else if (kind === SK.Decorator) {
visitor(modifier);
continue;
}

// at runtime skip the remaining checks
// these are here only as a compile-time exhaustive check
const trueAsFalse = /** @type {false} */ true;
if (trueAsFalse) continue;
// at runtime skip the remaining code, its purpose is a compile-time exhaustive check
if (true as false) continue;

switch (modifier.kind) {
switch (kind) {
case SK.ConstKeyword:
case SK.DefaultKeyword:
case SK.ExportKeyword:
Expand All @@ -286,7 +306,7 @@ function visitModifiers(modifiers: ArrayLike<ts.ModifierLike>): void {
case SK.OutKeyword:
continue;
default:
never(modifier);
never(kind);
}
}
}
Expand Down Expand Up @@ -345,6 +365,13 @@ function visitLegacyTypeAssertion(node: ts.TypeAssertion): VisitResult {
return visitor(node.expression);
}

const unsupportedParameterModifiers = new Set([
SK.PublicKeyword,
SK.ProtectedKeyword,
SK.PrivateKeyword,
SK.ReadonlyKeyword,
]);

/**
* `function<T>(p: T): T {}`
*/
Expand Down Expand Up @@ -374,22 +401,19 @@ function visitFunctionLikeDeclaration(node: ts.FunctionLikeDeclaration, kind: ts
// method?
node.questionToken && blankExact(node.questionToken);

for (let i = 0; i < node.parameters.length; i++) {
const p = node.parameters[i];
const params = node.parameters;
for (let i = 0; i < params.length; i++) {
const p = params[i];
if (i === 0 && p.name.getText(ast) === "this") {
blankExactAndOptionalTrailingComma(p);
continue;
}
if (p.modifiers) {
if (onError && p.modifiers) {
// error on non-standard parameter properties
for (let i = 0; i < p.modifiers.length; i++) {
const mod = p.modifiers[i];
switch (mod.kind) {
case SK.PublicKeyword:
case SK.ProtectedKeyword:
case SK.PrivateKeyword:
case SK.ReadonlyKeyword:
onError && onError(mod);
const modifier = p.modifiers[i];
if (unsupportedParameterModifiers.has(modifier.kind)) {
onError(modifier);
}
}
}
Expand All @@ -400,9 +424,9 @@ function visitFunctionLikeDeclaration(node: ts.FunctionLikeDeclaration, kind: ts
}

const returnType = node.type;
const isArrow = node.kind === SK.ArrowFunction;
const isArrow = kind === SK.ArrowFunction;
if (returnType) {
if (!isArrow || !spansLines(node.parameters.end, node.equalsGreaterThanToken.pos)) {
if (!isArrow || !spansLines(node.parameters.end, (node as ts.ArrowFunction).equalsGreaterThanToken.pos)) {
blankTypeNode(returnType);
} else {
// danger! new line between parameters and `=>`
Expand All @@ -413,13 +437,7 @@ function visitFunctionLikeDeclaration(node: ts.FunctionLikeDeclaration, kind: ts

const body = node.body;
if (body.kind === SK.Block) {
const statements = (body as ts.Block).statements;
const cache = seenJS;
seenJS = false;
for (let i = 0; i < statements.length; i++) {
visitStatementLike(statements[i]);
}
seenJS = cache;
visitNodeArray((body as ts.Block).statements, /* isStatementLike: */ true, /* isFunctionBody: */ true);
} else {
visitor(node.body);
}
Expand Down

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